Commit graph

58 commits

Author SHA1 Message Date
David Chinner
2a82b8be8a [XFS] Concurrent Multi-File Data Streams
In media spaces, video is often stored in a frame-per-file format. When
dealing with uncompressed realtime HD video streams in this format, it is
crucial that files do not get fragmented and that multiple files a placed
contiguously on disk.

When multiple streams are being ingested and played out at the same time,
it is critical that the filesystem does not cross the streams and
interleave them together as this creates seek and readahead cache miss
latency and prevents both ingest and playout from meeting frame rate
targets.

This patch set creates a "stream of files" concept into the allocator to
place all the data from a single stream contiguously on disk so that RAID
array readahead can be used effectively. Each additional stream gets
placed in different allocation groups within the filesystem, thereby
ensuring that we don't cross any streams. When an AG fills up, we select a
new AG for the stream that is not in use.

The core of the functionality is the stream tracking - each inode that we
create in a directory needs to be associated with the directories' stream.
Hence every time we create a file, we look up the directories' stream
object and associate the new file with that object.

Once we have a stream object for a file, we use the AG that the stream
object point to for allocations. If we can't allocate in that AG (e.g. it
is full) we move the entire stream to another AG. Other inodes in the same
stream are moved to the new AG on their next allocation (i.e. lazy
update).

Stream objects are kept in a cache and hold a reference on the inode.
Hence the inode cannot be reclaimed while there is an outstanding stream
reference. This means that on unlink we need to remove the stream
association and we also need to flush all the associations on certain
events that want to reclaim all unreferenced inodes (e.g. filesystem
freeze).

SGI-PV: 964469
SGI-Modid: xfs-linux-melb:xfs-kern:29096a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: Vlad Apostolov <vapo@sgi.com>
2007-07-14 15:40:53 +10:00
David Chinner
516b2e7c26 [XFS] Fix remount,readonly path to flush everything correctly.
The remount readonly path can fail to writeback properly because we still
have active transactions after calling xfs_quiesce_fs(). Further
investigation shows that this path is broken in the same ways that the xfs
freeze path was broken so fix it the same way.

SGI-PV: 964464
SGI-Modid: xfs-linux-melb:xfs-kern:28869a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-07-14 15:35:58 +10:00
David Chinner
92821e2ba4 [XFS] Lazy Superblock Counters
When we have a couple of hundred transactions on the fly at once, they all
typically modify the on disk superblock in some way.
create/unclink/mkdir/rmdir modify inode counts, allocation/freeing modify
free block counts.

When these counts are modified in a transaction, they must eventually lock
the superblock buffer and apply the mods. The buffer then remains locked
until the transaction is committed into the incore log buffer. The result
of this is that with enough transactions on the fly the incore superblock
buffer becomes a bottleneck.

The result of contention on the incore superblock buffer is that
transaction rates fall - the more pressure that is put on the superblock
buffer, the slower things go.

The key to removing the contention is to not require the superblock fields
in question to be locked. We do that by not marking the superblock dirty
in the transaction. IOWs, we modify the incore superblock but do not
modify the cached superblock buffer. In short, we do not log superblock
modifications to critical fields in the superblock on every transaction.
In fact we only do it just before we write the superblock to disk every
sync period or just before unmount.

This creates an interesting problem - if we don't log or write out the
fields in every transaction, then how do the values get recovered after a
crash? the answer is simple - we keep enough duplicate, logged information
in other structures that we can reconstruct the correct count after log
recovery has been performed.

It is the AGF and AGI structures that contain the duplicate information;
after recovery, we walk every AGI and AGF and sum their individual
counters to get the correct value, and we do a transaction into the log to
correct them. An optimisation of this is that if we have a clean unmount
record, we know the value in the superblock is correct, so we can avoid
the summation walk under normal conditions and so mount/recovery times do
not change under normal operation.

One wrinkle that was discovered during development was that the blocks
used in the freespace btrees are never accounted for in the AGF counters.
This was once a valid optimisation to make; when the filesystem is full,
the free space btrees are empty and consume no space. Hence when it
matters, the "accounting" is correct. But that means the when we do the
AGF summations, we would not have a correct count and xfs_check would
complain. Hence a new counter was added to track the number of blocks used
by the free space btrees. This is an *on-disk format change*.

As a result of this, lazy superblock counters are a mkfs option and at the
moment on linux there is no way to convert an old filesystem. This is
possible - xfs_db can be used to twiddle the right bits and then
xfs_repair will do the format conversion for you. Similarly, you can
convert backwards as well. At some point we'll add functionality to
xfs_admin to do the bit twiddling easily....

SGI-PV: 964999
SGI-Modid: xfs-linux-melb:xfs-kern:28652a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-07-14 15:28:50 +10:00
David Chinner
40095b64f5 [XFS] Sleeping with the ilock waiting for I/O completion is Bad.
Recent fixes to the filesystem freezing code introduced a vn_iowait call
in the middle of the sync code. Unfortunately, at the point where this
call was added we are holding the ilock. The ilock is needed by I/O
completion for unwritten extent conversion and now updating the file size.
Hence I/o cannot complete if we hold the ilock while waiting for I/O
completion.

Fix up the bug and clean the code up around it.

SGI-PV: 963674
SGI-Modid: xfs-linux-melb:xfs-kern:28566a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-07-14 15:22:18 +10:00
Lachlan McIlroy
f7c66ce3f7 [XFS] Add lockdep support for XFS
SGI-PV: 963965
SGI-Modid: xfs-linux-melb:xfs-kern:28485a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-05-08 13:50:19 +10:00
Lachlan McIlroy
d3cf209476 [XFS] propogate return codes from flush routines
This patch handles error return values in fs_flush_pages and
fs_flushinval_pages. It changes the prototype of fs_flushinval_pages so we
can propogate the errors and handle them at higher layers. I also modified
xfs_itruncate_start so that it could propogate the error further.

SGI-PV: 961990
SGI-Modid: xfs-linux-melb:xfs-kern:28231a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Stewart Smith <stewart@flamingspork.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-05-08 13:49:27 +10:00
Eric Sandeen
1c72bf9003 [XFS] The last argument "lsn" of xfs_trans_commit() is always called with
NULL.

Patch provided by Eric Sandeen.

SGI-PV: 961693
SGI-Modid: xfs-linux-melb:xfs-kern:28199a

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-05-08 13:48:42 +10:00
David Chinner
3c0dc77b42 [XFS] Make freeze code a little cleaner.
Fixes a few small issues (mostly cosmetic) that were picked up during the
review cycle for the last set of freeze path changes.

SGI-PV: 959267
SGI-Modid: xfs-linux-melb:xfs-kern:28035a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-02-10 18:37:22 +11:00
David Chinner
2823945fda [XFS] Ensure a frozen filesystem has a clean log before writing the dummy
record.

The current Linux XFS freeze code is a mess. We flush the metadata buffers
out while we are still allowing new transactions to start and then fail to
flush the dirty buffers back out before writing the unmount and dummy
records to the log.

This leads to problems when the frozen filesystem is used for snapshots -
we do log recovery on a readonly image and often it appears that the log
image in the snapshot is not correct. Hence we end up with hangs, oops and
mount failures when trying to mount a snapshot image that has been created
when the filesystem has not been correctly frozen.

To fix this, we need to move th metadata flush to after we wait for all
current transactions to complete in teh second stage of the freeze. This
means that when we write the final log records, the log should be clean
and recovery should never occur on a snapshot image created from a frozen
filesystem.

SGI-PV: 959267
SGI-Modid: xfs-linux-melb:xfs-kern:28010a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-02-10 18:36:40 +11:00
David Chinner
dbcabad19a [XFS] Fix block reservation mechanism.
The block reservation mechanism has been broken since the per-cpu
superblock counters were introduced. Make the block reservation code work
with the per-cpu counters by syncing the counters, snapshotting the amount
of available space and then doing a modifcation of the counter state
according to the result. Continue in a loop until we either have no space
available or we reserve some space.

SGI-PV: 956323
SGI-Modid: xfs-linux-melb:xfs-kern:27895a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-02-10 18:36:17 +11:00
Lachlan McIlroy
1f9b3b64d4 [XFS] remove unused xflags parameter from sync routines
SGI-PV: 959137
SGI-Modid: xfs-linux-melb:xfs-kern:27710a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2007-02-10 18:35:33 +11:00
Nathan Scott
215101c360 [XFS] Fix kmem_zalloc_greedy warnings on 64 bit platforms.
SGI-PV: 955302
SGI-Modid: xfs-linux-melb:xfs-kern:26907a

Signed-off-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
2006-09-28 11:04:43 +10:00
David Chinner
4be536debe [XFS] Prevent free space oversubscription and xfssyncd looping.
The fix for recent ENOSPC deadlocks introduced certain limitations on
allocations. The fix could cause xfssyncd to loop endlessly if we did not
leave some space free for the allocator to work correctly. Basically, we
needed to ensure that we had at least 4 blocks free for an AG free list
and a block for the inode bmap btree at all times.

However, this did not take into account the fact that each AG has a free
list that needs 4 blocks. Hence any filesystem with more than one AG could
cause oversubscription of free space and make xfssyncd spin forever trying
to allocate space needed for AG freelists that was not available in the
AG.

The following patch reserves space for the free lists in all AGs plus the
inode bmap btree which prevents oversubscription. It also prevents those
blocks from being reported as free space (as they can never be used) and
makes the SMP in-core superblock accounting code and the reserved block
ioctl respect this requirement.

SGI-PV: 955674
SGI-Modid: xfs-linux-melb:xfs-kern:26894a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: David Chatterton <chatz@sgi.com>
2006-09-07 14:26:50 +10:00
Nathan Scott
b2ea401bac [XFS] Fix a barrier related forced shutdown on mounts with quota enabled.
SGI-PV: 912426
SGI-Modid: xfs-linux-melb:xfs-kern:26622a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-07-28 17:05:13 +10:00
Nathan Scott
f6c2d1fa63 [XFS] Remove version 1 directory code. Never functioned on Linux, just
pure bloat.

SGI-PV: 952969
SGI-Modid: xfs-linux-melb:xfs-kern:26251a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-06-20 13:04:51 +10:00
Nathan Scott
b190f1138b [XFS] Fix broken const use inside local suffix_strtoul routine.
SGI-PV: 904196
SGI-Modid: xfs-linux-melb:xfs-kern:26201a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-06-09 17:13:15 +10:00
Nathan Scott
8285fb58e7 [XFS] Resolve a namespace collision on remaining vtypes for FreeBSD
porters.

SGI-PV: 953338
SGI-Modid: xfs-linux-melb:xfs-kern:26108a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-06-09 17:07:12 +10:00
Nathan Scott
67fcaa73ad [XFS] Resolve a namespace collision on vnode/vnodeops for FreeBSD porters.
SGI-PV: 953338
SGI-Modid: xfs-linux-melb:xfs-kern:26107a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-06-09 17:00:52 +10:00
Nathan Scott
b83bd13881 [XFS] Resolve a namespace collision on vfs/vfsops for FreeBSD porters.
SGI-PV: 9533338
SGI-Modid: xfs-linux-melb:xfs-kern:26106a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-06-09 16:48:30 +10:00
Nathan Scott
b65745205f [XFS] Portability changes: remove prdev, stick to one diagnostic
interface.

SGI-PV: 953338
SGI-Modid: xfs-linux-melb:xfs-kern:26103a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-06-09 15:29:40 +10:00
Nathan Scott
d08d389d5a [XFS] Fix a possible forced shutdown due to mishandling write barriers
with remount,ro.

SGI-PV: 951944
SGI-Modid: xfs-linux-melb:xfs-kern:25742a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-05-08 19:51:28 +10:00
Nathan Scott
3bbcc8e397 [XFS] Reenable write barriers by default.
SGI-PV: 912426
SGI-Modid: xfs-linux-melb:xfs-kern:25634a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-31 13:04:56 +10:00
Nathan Scott
764d1f89a5 [XFS] Implement the silent parameter to fill_super, previously ignored.
SGI-PV: 951299
SGI-Modid: xfs-linux-melb:xfs-kern:25632a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-31 13:04:17 +10:00
Nathan Scott
c41564b5af [XFS] We really suck at spulling. Thanks to Chris Pascoe for fixing all
these typos.

SGI-PV: 904196
SGI-Modid: xfs-linux-melb:xfs-kern:25539a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-29 08:55:14 +10:00
Nathan Scott
e15f195cfb [XFS] Reenable the noikeep (delete inode cluster space) option by default.
SGI-PV: 951200
SGI-Modid: xfs-linux-melb:xfs-kern:25535a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-22 12:47:52 +11:00
Nathan Scott
3758dee9f6 [XFS] Fixup naming inconsistencies found by Pekka Enberg and one from Jan
Engelhardt.

SGI-PV: 947038
SGI-Modid: xfs-linux-melb:xfs-kern:25529a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-22 12:47:28 +11:00
Nathan Scott
b12dd34298 [XFS] Fix an infinite loop issue in bulkstat when a corrupt inode is
detected.  Thanks to Roger Willcocks.

SGI-PV: 951054
SGI-Modid: xfs-linux-melb:xfs-kern:25477a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-17 17:26:04 +11:00
Nathan Scott
8758280fcc [XFS] Cleanup the use of zones/slabs, more consistent and allows flags to
be passed.

SGI-PV: 949073
SGI-Modid: xfs-linux-melb:xfs-kern:25122a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-14 13:18:19 +11:00
David Chinner
8d280b98cf [XFS] On machines with more than 8 cpus, when running parallel I/O
threads, the incore superblock lock becomes the limiting factor for
buffered write throughput. Make the contended fields in the incore
superblock use per-cpu counters so that there is no global lock to limit
scalability.

SGI-PV: 946630
SGI-Modid: xfs-linux-melb:xfs-kern:25106a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-14 13:13:09 +11:00
Nathan Scott
9f4cbecd7e [XFS] XFS propagates MS_NOATIME through two levels internally but doesn't
actually use it.  Kill this dead code.	Signed-off-by: Christoph Hellwig
<hch@lst.de>

SGI-PV: 904196
SGI-Modid: xfs-linux-melb:xfs-kern:25086a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-03-14 13:05:30 +11:00
Nathan Scott
c2cd255060 [XFS] Fix v2 log bufsize reporting in /proc/mounts.
SGI-PV: 946760
SGI-Modid: xfs-linux-melb:xfs-kern:24765a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-01-11 15:35:32 +11:00
Nathan Scott
b04ed21a1f [XFS] Disable write barriers for now till intermittent IO errors are
understood.

SGI-PV: 912426
SGI-Modid: xfs-linux-melb:xfs-kern:202962a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-01-11 15:32:17 +11:00
Nathan Scott
13059ff04c [XFS] Reverse the sense of COMPAT_ATTR and ATTR2, keeps it simple and
consistent.

SGI-PV: 941645
SGI-Modid: xfs-linux-melb:xfs-kern:202961a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-01-11 15:32:01 +11:00
Christoph Hellwig
e13a73f025 [XFS] Write log dummy record when freezing filesystem
SGI-PV: 945483
SGI-Modid: xfs-linux-melb:xfs-kern:202638a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-01-11 15:30:08 +11:00
Christoph Hellwig
c7d437da3d [XFS] do barrier checks earlier. quota initialization may write to the
filesystem

SGI-PV: 912426
SGI-Modid: xfs-linux-melb:xfs-kern:202355a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-01-11 15:28:56 +11:00
Nathan Scott
70a061f1fd [XFS] Fix typo from when enabling write barriers by default, flags botch
in showargs.

SGI-PV: 912426
SGI-Modid: xfs-linux-melb:xfs-kern:24383a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-01-11 15:28:45 +11:00
Christoph Hellwig
4ef19dddba [XFS] enable write barriers by default
SGI-PV: 912426
SGI-Modid: xfs-linux-melb:xfs-kern:201981a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
2006-01-11 15:27:18 +11:00
Nathan Scott
05db218a27 [XFS] Fix an inode32 regression - if no options are presented, must still
set default flags.

SGI-PV: 945242
SGI-Modid: xfs-linux-melb:xfs-kern:24292a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-04 09:49:07 +11:00
Nathan Scott
cfcbbbd089 [XFS] Remove old, broken nolog-mode code - noone plans to ever fix it.
SGI-PV: 944821
SGI-Modid: xfs-linux:xfs-kern:24213a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 15:12:04 +11:00
Nathan Scott
c11e2c369d [XFS] Rework fid encode/decode wrt 64 bit inums interacting with NFS.
SGI-PV: 937127
SGI-Modid: xfs-linux:xfs-kern:24201a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 15:11:45 +11:00
Nathan Scott
e718eeb4fe [XFS] Rework the final mount options flag bit to make room for more.
SGI-PV: 943866
SGI-Modid: xfs-linux:xfs-kern:24030a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 15:09:22 +11:00
Nathan Scott
8a319ae494 [XFS] Disable attr2 by default, until a more appropriate time to enable
it.

SGI-PV: 941645
SGI-Modid: xfs-linux:xfs-kern:24002a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 15:07:51 +11:00
Nathan Scott
fa7e7d71e0 [XFS] Show additional mount options in /proc/mounts, fix up some debug
code.

SGI-PV: 941645
SGI-Modid: xfs-linux:xfs-kern:23926a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 15:00:48 +11:00
Nathan Scott
7b71876980 [XFS] Update license/copyright notices to match the prefered SGI
boilerplate.

SGI-PV: 913862
SGI-Modid: xfs-linux:xfs-kern:23903a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 14:58:39 +11:00
Nathan Scott
a844f4510d [XFS] Remove xfs_macros.c, xfs_macros.h, rework headers a whole lot.
SGI-PV: 943122
SGI-Modid: xfs-linux:xfs-kern:23901a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 14:38:42 +11:00
Nathan Scott
fc1f8c1ca3 [XFS] Track external log/realtime device names for correct reporting in
/proc/mounts.

SGI-PV: 942984
SGI-Modid: xfs-linux:xfs-kern:23862a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 11:44:33 +11:00
Nathan Scott
d8cc890d40 [XFS] Ondisk format extension for extended attributes (attr2). Basically,
the data/attr forks now grow up/down from either end of the literal area,
rather than dividing the literal area into two chunks and growing both
upward.  Means we can now make much more efficient use of the attribute
space, incl. fitting DMF attributes inline in 256 byte inodes, and large
jumps in dbench3 performance numbers.  It is self enabling, but can be
forced on/off via the attr2/noattr2 mount options.

SGI-PV: 941645
SGI-Modid: xfs-linux:xfs-kern:23835a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 10:34:53 +11:00
David Chinner
e8c8b3a79d [XFS] Introduce two new mount options (nolargeio/largeio) to allow
filesystems to expose the filesystem stripe width in stat(2) rather than
the page cache size. This allows applications requiring high bandwidth to
easily determine the optimum I/O size for the underlying filesystem. The
default is to report the page cache size (i.e. "nolargeio").

SGI-PV: 942818
SGI-Modid: xfs-linux:xfs-kern:23830a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 10:33:05 +11:00
Nathan Scott
ee34807a65 [XFS] Provide a mechiansm for flushing delalloc before quota reporting.
SGI-PV: 942815
SGI-Modid: xfs-linux:xfs-kern:23829a

Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 10:32:38 +11:00
Christoph Hellwig
f538d4da8d [XFS] write barrier support Issue all log sync operations as ordered
writes.  In addition flush the disk cache on fsync if the sync cached
operation didn't sync the log to disk (this requires some additional
bookeping in the transaction and log code). If the device doesn't claim to
support barriers, the filesystem has an extern log volume or the trial
superblock write with barriers enabled failed we disable barriers and
print a warning.  We should probably fail the mount completely, but that
could lead to nasty boot failures for the root filesystem.  Not enabled by
default yet, needs more destructive testing first.

SGI-PV: 912426
SGI-Modid: xfs-linux:xfs-kern:198723a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
2005-11-02 10:26:59 +11:00